The present invention is directed to a metal-gas battery, specifically a metal-gas battery with a cathode comprising nitric oxide (NO) as an active material.
Lithium ion batteries have been in commercial use since 1991 and have been conventionally used as power sources for portable electronic devices. The technology associated with the construction and composition of the lithium ion battery (LIB) has been the subject of investigation and improvement and has matured to an extent where a state of art LIB battery is reported to have up to 700 Wh/L of energy density. However, even the most advanced LIB technology is not considered to be viable as a power source capable to meet the demands for a commercial electric vehicle (EV) in the future. For example, for a 300 mile range EV to have a power train equivalent to current conventional internal combustion engine vehicles, an EV battery pack having an energy density of approximately 2000 Wh/L is required. As this energy density is close to the theoretical limit of a lithium ion active material, technologies which can offer battery systems of higher energy density are under investigation.
Metal-air batteries are one of the technologies under investigation as a potential advancement in energy technology to supplant and replace the lithium ion battery for several reasons. In a metal-air battery the positive electrode active material is oxygen gas which conceptually may be obtained from the air. As such, much of the mass of the battery associated with the cathode component is significantly reduced. Interest in metal-air batteries is also supported by the concept that O2 gas is continuously coming from outside of the battery, and therefore, the battery performance in terms of capacity and lifetime would be determined by the metal anode. Theoretically, such a battery would function until the metal anode is consumed and as a result, the metal-air battery may have higher energy density potential than other battery technologies presently under investigation.
Due to the known energy potential of lithium, a Li—O2 battery is of interest as a candidate high energy density type rechargeable battery. Li—O2 batteries based on a source of purified O2 have been demonstrated. However, when ambient air is employed as the oxygen source, the battery performance deteriorates and utility as a rechargeable battery is lost. This deterioration is believed to occur because the presence of H2O and CO2 in air causes deactivation of lithium oxides such as Li2O2 and Li2O, by formation of Li2CO3, which is an inactive material for recharging. Thus, a major challenge to the success of a Li—O2 battery is the necessity for purification of O2 gas from ambient air or atmosphere. Generally, a battery consuming pure oxygen would not be practicable for conventional consumer utility. However, with currently known technologies, the presence of H2O and CO2 prevent successful development of a commercially useful battery.
One of the approaches to overcome this issue is removal of H2O and CO2 through membrane technologies. Air management is necessary to implement the gas purification. However, the purification required seems to be quite difficult even using the state-of-art gas separation membrane technology. Further, it may be possible to eliminate H2O and CO2 employing gas absorption, for example on a zeolite, however, such a gas absorption system would be too large to be considered a realistic solution in most battery applications.
In view of the problems associated with a metal-O2 battery, effort is underway to develop alternative cathode systems for a metal-gas battery.
Albertus et al. (U.S. 2012/0094193) describes an electrochemical metal-gas cell having a lithium negative electrode and an oxygen/carbon dioxide active cathode material. The oxygen/carbon dioxide mixture is based on ambient air and includes CO2. According to Albertus, a specific ratio of CO2/O2, 2:1 is necessary to achieve high energy density as a primary battery. However, except for the exhaust gas from a factory or other large stationary exhaust sources, it is difficult to concentrate the CO2 gas to such ratio, because in ambient air, the quantity of CO2 is approximately 0.03%. It may be possible to devise an air control system to meet this requirement in a fixed construction, although an air management system which maintains a constant CO2 concentration is not conventionally available. However, for use in an automobile, such a battery would not be practical because the CO2 concentration fluctuates and control to a specific ratio would be difficult.
Takechi et al. (JP 2011-070835) describes a metal air cell wherein the anode metal may be lithium, sodium, potassium, magnesium, calcium, aluminum or zinc. The oxidant supplied to the cathode is a combination of oxygen and carbon dioxide.
Hillhouse (U.S. 2013/0216924) describes a capacitor device for generating electrical power wherein a fuel is flowed over a working electrode of the capacitor, thus charging the capacitor. The flow is then reversed and an oxidant is flowed over the working electrode, thus generating current flow across the electrodes. Materials listed as fuels which can act as electron sources include hydrogen, carbon monoxide, NO, NO2, SO2 and volatile hydrocarbons.
Hiraiwa et al. (U.S. 2013/0089810) describes an electrochemical reaction apparatus for fluid flow decomposition of an ammonia containing stream, wherein the NH3 is converted to N2 and water when air or oxygen is coupled as an oxidant. Electric power may be generated due to a potential difference between the apparatus anode and cathode. The apparatus is in the form of a membrane electrode assembly (MEA) and functions as a fuel cell, not as a battery.
Lee et al. (U.S. 2012/0141889) describes a lithium air battery containing an organic electrolyte which includes a metal-ligand complex. The negative electrode contains lithium and the positive electrode contains oxygen from an external supply. The metal-ligand complex has a charge/discharge voltage range which falls within the range of a lithium battery and may transfer electrons via formation of redox couples during the charging and discharging cycles. Air or oxygen are the only cathode active materials disclosed.
Huang (U.S. 2010/0247981) describes a system for energy management of a composite battery (fuel cell). The system includes a series of modules for collecting off-gas from the fuel cell, analyzing the content of the off-gas and then directing the off-gas to a point of further fuel consumption. For example, where the off-gas contains hydrogen it may be consumed in an internal combustion engine or a hydrogen fuel cell.
Limaye (U.S. Pat. No. 5,976,721) describes a chemical cogeneration process which is conducted in a specially constructed monolithic mass having sets of passageways. A fuel such as hydrogen sulfide, ammonia or a hydrocarbon is introduced into one passageway, and an oxidant such as air, a nitrogen oxide, carbon dioxide, sulfur dioxide, sulfur trioxide or steam is introduced to a second passageway. The passageways are constructed of electrically conducting materials which are connected to an external electrical circuit.
Langer et al. (U.S. Pat. No. 4,321,313) describes the electrogenerative reduction of nitric oxide by reaction with hydrogen in the presence of electrocatalytic electrodes and electrolyte. As described the electrogenerative cell is an electrochemical reactor which is similar to a fuel cell.
Smith et al. (U.S. Pat. No. 3,979,225) describes a fuel cell based on a cathodic reduction of nitrogen dioxide (NO2) to nitric oxide (NO). Then NO is captured and reoxidized to nitrogen dioxide for recycle back to the cathode of the fuel cell. Hydrogen gas or reformed hydrocarbon gas stream are disclosed as the anode reactant, however, any other anode half reaction may be coupled with the cathodic reduction.
Liang et al. (CN102371888) (Abstract only) describes a plasma generator which is effective to remove nitric oxide from an exhaust gas of a gasoline engine. Although the NO is passed between electrodes, utility as a battery is not disclosed.
Wen et al. (CN102208653) (Abstract only) describes a lithium air battery having an air electrode which contains a catalyst, a carrier and an adhesive.
Park (KR20090026589) describes fuel-cell based post processor to remove nitric oxides for an exhaust system of an engine.
Therefore, there is a need to find and develop alternative cathodic gases for a metal-gas battery which are safe, readily available and cost efficient.